Faculty Bibliography

OBJECTIVES:To (1) report the thermal changes encountered at the pin/skin interface in a cadaver with a knee-spanning external fixator inside the magnetic resonance imaging (MRI) bore and (2) report on the quality of the MRI sequences collected. METHODS:Three commonly used external fixation systems were placed on cadaveric lower extremities to simulate knee external fixation. Fiber optic thermal probes were placed at the pin/skin interface of a femoral and tibial pin. A control probe was embedded in the soft tissues of the thigh. Full knee MRI scans were performed using a 1.5-Tesla magnet. Real-time thermal data were collected. A clinically significant increase in temperature compared with the control was defined as 2°C. Two blinded radiologists evaluated the images for image quality and overall diagnostic utility using a standardized 5-point grading scale. RESULTS:There were statistically significant differences in the temperature changes between the femoral/tibial pin sites and the control probe sites during each phase of the MRI scan. However, there was only one clinically significant difference in temperature change during a single sequence of one MRI scan of one of the external fixator devices. Overall image quality was graded as a 4 for each image set with 100% interobserver agreement (k = 1.0). CONCLUSIONS:Despite significant differences in temperature changes between the pin sites and controls over multiple MRI sequences in commonly used external fixator devices, the differences in temperature change are likely not clinically relevant. Overall image quality and interpretability of the images were excellent.

The goal of operative intervention for pantrapezial arthritis is to relieve pain, maintain or improve motion, stability, and strength, and restore function. The purpose of this article is to present a volar approach to thumb carpometacarpal suspension arthroplasty using an absorbable interference screw for flexor carpi radialis ligament reconstruction and tendon interposition in the treatment of pantrapezial arthritis. This technique allows for visualization of the volar beak and avoidance of the radial artery and the branches of the superficial radial nerve while allowing optimal surgical manipulation for suspensionplasty with interference screw fixation and tendon interposition at the carpometacarpal joint.